1. Field of the Invention
The present invention relates to a method and system for reducing the emission of PFC""s (perfluoro compounds) during semiconductor manufacturing processes.
2. Background of the Invention
Effluent gases emitted during semiconductor manufacturing processes, for example during CVD chamber cleaning and dry etch processes, frequently contain perfluoro compounds (PFC""s). PFC""s are global warming gases, and significant efforts have been and are continuing to be made to reduce and minimize the amount of PFC""s that are emitted into the atmosphere. In particular, a convention of the World Semiconductor Council, including the United States, Europe, Japan, Taiwan and Korea, seeks to reduce the amount of PFC emission by 10% by the year 2010, with the following basis years: United States, Europe, Japan: 1995; Korea: 1997; Taiwan: 1998.
Known procedures for reducing the amount of PFC emission include use of abatement scrubbers, capture and recycle, use of alternative process gases, and process optimization. Common types of abatement scrubbers useful for the removal of PFC""s include (a) combustion-type scrubbers with LNG, LPG, H2 and/or CH4, (b) chemisorption-type scrubbers using metal oxides and physical adsorption-type scrubbers using active carbon or zeolite surfaces, and (c) decomposition-type scrubbers using a plasma.
Certain known emission reduction processes, as illustrated in FIG. 1, use separate abatement scrubbers 2 for each individual process component 1 (e.g., etch chambers 3, CVD reactors 4) before emission of the treated gas streams. Such processes, however, are expected to increase the overall cost of the semiconductor manufacturing process. Furthermore, it may be difficult to integrate the various abatement scrubbers into existing process layouts and to maintain the scrubbers once they are installed.
Capture and recycle systems, such as the system of FIG. 2, direct process streams from, e.g., etch chambers 3 and CVD reactors 4 to a wet scrubbing system 5, then through a membrane 6 for separation and recycle of PFC gases and recovery of other process gases such as nitrogen. Such systems typically require pretreatment of powder components to remove moisture, as well as a powder removal system 7 downstream from the wet scrubbing system 5. Furthermore, the amounts of PFC""s actually recycled typically is small due to the small amounts of PFC""s that are captured. Moreover, if recycling proves impossible, another system must be employed to dispose of the captured PFC""s.
Use of alternative process gases and process optimization have also proven problematic due to the insufficiency of suitable alternative gases and low process yield.
A continuing need exists for an improved process for reducing and minimizing the amounts of PFC""s emitted during semiconductor manufacturing processes.
In accordance with one aspect of the present invention, a method of reducing PFC emissions during a semiconductor manufacturing process that has a plurality of sub-processes (e.g., dry etches, CVD) includes the steps of: exhausting PFC""s produced by each sub-process to a common line; treating each combined exhaust stream using a PFC abatement system; combining the treated exhaust streams to form a combined treated stream; and wet scrubbing the combined treated stream.
In accordance with another aspect of the present invention, a method of reducing PFC emissions during a semiconductor manufacturing process that has a plurality of sub-processes including at least one etching sub-process and at least one CVD sub-process includes the steps of: exhausting PFC""s produced by each etching sub-process to a first common line to form a combined etching exhaust stream; treating the combined etching exhaust stream using a first PFC abatement system; exhausting PFC""s produced by each CVD sub-process to a second common line to form a combined CVD exhaust stream; treating the combined CVD exhaust stream using a second PFC abatement system; combining the treated combined etching exhaust stream and the treated combined CVD exhaust stream to form a combined treated stream; and wet scrubbing the combined treated stream.
According to a further aspect of the present invention, a system for reducing PFC emissions during a semiconductor manufacturing process that has a plurality of sub-processes includes: a first plurality of devices for carrying out a first subprocess; a first common line for PFC""s exhausted from the first plurality of devices; a first PFC abatement system connected to the first common line; a second plurality of devices for carrying out a second sub-process; a second common line for PFC""s exhausted from the second plurality of devices; a second PFC abatement system connected to the second common line; a common treated exhaust line connected to the first and second PFC abatement systems; and a wet scrubbing system connected to the common treated exhaust line.
According to an additional aspect of the present invention, a system for reducing PFC emissions during a semiconductor manufacturing process that includes a first plurality of etching sub-processes and at least one CVD sub-process, each of which produces at least one PFC. The system includes: a first plurality of devices comprising at least one device for carrying out each of the first plurality of etching sub-process; a sub-process common line associated with each etching sub-process for PFC""s exhausted from the at least one device for carrying out each of the etching sub-processes; a first common line for receiving PFC""s exhausted from the first plurality of devices; a first PFC abatement system connected to the first common line; a second plurality of devices for carrying out the at least one CVD sub-process; a second common line for PFC""s exhausted from the second plurality of devices; a second PFC abatement system connected to the second common line; a common treated exhaust line connected to the first and second PFC abatement systems; and a wet scrubbing system connected to the common treated exhaust line.
In more particular embodiments, sensors for the detection and measurement of PFC""s are disposed at the inlets and/or outlets of the PFC abatement systems.
Other features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.